Experimental Investigation of the Effect of Positive Slope of the Horizontal Screen on Hydraulic Characteristics of Vertical Drop

Document Type : Research Paper


1 Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Iran.

2 Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.


In the present study, 105 tests were carried out to investigate the effect of horizontal screen slope on hydraulic characteristics of vertical drop with the subcritical flow in upstream. The experiments were arranged in two models, plain vertical drop and vertical drop equipped with horizontal and sloping (three slopes) screens in two porosity ratios. The range of relative critical depth was from 0.07 to 0.24 the screen slopes were 7, 14, 21, and the screen porosities  were considered to be 40% and 50%. The relative wetted length of the screen, the relative turbulance length, the relative depth of pool, the relative downstream depth, and the relative residual energy were analyzed. In all cases, by increasing the relative critical depth, the turbulance length, pool depth, downstream depth, and relative residual energy were increased. The results showed by increasing the slope of  screen, the characteristics of the relative wetted length of the horizontal screen, relative turbulance length, and relative pool depth increases. However, the slope of screen has no effect on the relative downstream depth and the relative residual energy. It was also observed that with increasing porosity ratio of the screen, the characteristics of the relative wetted length of the horizontal screen, relative turbulance length, and relative pool depth decreases, and the relative downstream depth increases. But the porosity of screens has an insignificant effect on the relative residual energy.


Main Subjects

Aslankara, V. (2007). Experimental investigation of tailwater effect on the energy dissipation through screens (Doctoral dissertation, MS thesis, Middle East Technical Univ. Ankara, Turkey).
Balkış, G. (2004). Experimental Investigation of Energy Dissipation through Inclined Screens (Doctoral dissertation, Middle East Technical Univercity, Ankara, Turkey).
Çakir, P. (2003). Experimental investigation of energy dissipation through screens (Doctoral dissertation, M. Sc. thesis, Department of Civil Engineering, Middle East Technical University, Ankara, Turkey).
Daneshfaraz, R., Sadeghfam, S., & Ghahramanzadeh, A. (2017a). Three-dimensional numerical investigation of flow through screens as energy dissipators. Canadian Journal of Civil Engineering, 44(10), 850-859.
Daneshfaraz, R., Sadeghfam, S. and Rezazadeh, J.A., (2017b). Laboratory Investigation on the Effect of Screen’s Location on the Flow Energy Dissipation. Irrigation and Drainage Structures Engineering Research, 17(67), 47-62 (in Farsi).
Daneshfaraz, R., Sadeghfam, S., Hasanniya, V. (2019a). Experimental Investigation of Energy Dissipation in Vertical Drops Equipped with a Horizontal Screen under Supercritical Flow, Iranian Journal of Soil and Water Research, 50(6), pp. 1421-1436. doi:10.22059/ijswr.2019.269301.668053.
Daneshfaraz, R., Sadeghfam, S. and Tahni, A. (2019b).Experimental investigation of screen as energy dissipators in the movable-bed channel”. Iranian Journal of Science and Technology, Transactions of Civil Engineering, doi.org/10. 1007/s40996-019-00306-7.
Daneshfaraz, R., Chabokpour, J. and Nezafat, H. (2019c). Experimental investigation of the scouring due to hydraulic jump in screens. Iranian Journal of Soil and Water Research, 50(5), 1039-1051(in Farsi).
Daneshfaraz, R., Majedi Asl, M. and Mirzaee, R., (2019d). Experimental study of expanding effect and sand-roughened bed on hydraulic jump characteristics. Iranian Journal of Soil and Water Research, 50(4), 885-896(in Farsi).
Daneshfaraz, R., Sadeghfam, S. and Minaei, O. (2020a).  Experimental Study of Energy Dissipation in the Stilling Basin with Movable Bed in the Upstream of Screens. Iranian Journal of Soil and Water Research, 50(9), 2113-2123, (In Persian).
Daneshfaraz, R., Majedi Asl, M., Razmi, S., Norouzi, R. and Abraham, J. (2020b). Experimental investigation of the effect of dual horizontal screens on the hydraulic performance of a vertical drop. International Journal of Environmental Science and Technology, doi.org/10.1007/s13762-019-02622-x,1-10.
Esen, I. I., Alhumoud, J. M., & Hannan, K. A. (2004). Energy Loss at a Drop Structure with a Step at the Base. Water international, 29(4), 523-529.
Hasanniya, V. (2019). Experimental investigation of flow energy dissipation through the screens application in drops. Master's thesis, Civil Engineering Department, Faculty of Engineering, University of Maragheh, Maragheh, Iran, (In Persian).
Hasannia, V., Daneshfaraz, R., Sadeghfam, S. (2019). Experimental investigating on hydraulic parameters of vertical drop equipped with combined screens. Amirkabir Journal of Civil Engineering, doi: 10.22060/ceej.2019.16431.6223
Hong, Y. M., Huang, H. S., & Wan, S. (2010). Drop characteristics of free-falling nappe for aerated straight-drop spillway. Journal of Hydraulic Research, 48(1), 125-129.
Kabiri-Samani, A. R., Bakhshian, E., & Chamani, M. R. (2017). Flow characteristics of grid drop-type dissipators. Flow Measurement and Instrumentation, 54, 298-306.
Liu, S. I., Chen, J. Y., Hong, Y. M., Huang, H. S., & Raikar, R. V. (2014). Impact Characteristics of Free Over-Fall in Pool Zone with Upstream Bed Slope. Journal of Marine Science and Technology, 22(4), 476-486.
Nayebzadeh, B., Lotfollahi-yaghin, M.A. and Daneshfaraz, R. (2019). Experimental study of energy dissipation at a vertical drop equipped with vertical screen with gradually expanding at the downstream. Amirkabir Journal of Civil Engineering. https://doi.org/10.22060/CEEJ.2019 .16493.6265.
Norouzi Sarkarabad, R., Daneshfaraz, R. and Bazyar, A. (2019). The Study of Energy Depreciation due to the use of Vertical Screen in the Downstream of Inclined Drops by Adaptive Neuro-Fuzzy Inference System (ANFIS). Amirkabir Journal of Civil Engineering. https://doi.org/10.22060/CEEJ. 2019.16694.6305.
Rajaratnam, N., & Chamani, M. R. (1995). Energy loss at drops. Journal of Hydraulic Research, 33(3), 373-384.
Rajaratnam, N., & Hurtig, K. I. (2000). Screen-type energy dissipator for hydraulic structures. Journal of Hydraulic Engineering, 126(4), 310-312.
Sadeghfam, S., Akhtari, A. A., Daneshfaraz, R., & Tayfur, G. (2015). Experimental investigation of screens as energy dissipaters in submerged hydraulic jump. Turkish Journal of Engineering and Environmental Sciences, 38(2), 126-138.
Sadeghfam, S., Daneshfaraz, R., Khatibi, R. and Minaei, O., 2019. Experimental studies on scour of supercritical flow jets in upstream of screens and modelling scouring dimensions using artificial intelligence to combine multiple models (AIMM). Journal of Hydroinformatics, 21(5), 893-907.
Sharif, M., & Kabiri-Samani, A. (2018). Flow regimes at grid drop-type dissipators caused by changes in tail-water depth. Journal of Hydraulic Research, 1-12.